1. Technical Field
This application generally relates to port virtualization and more particularly to techniques for providing one or more logical or virtual connections over a single physical connection.
2. Description of Related Art
Computer systems may include different resources used by one or more host processors. Resources and host processors in a system may be interconnected by one or more communication connections. These resources may include, for example, data storage devices such as those included in the data storage systems manufactured by EMC Corporation. These data storage systems may be coupled to one or more host processors and provide storage services to each host processor. Multiple data storage systems from one or more different vendors may be connected and may provide common data storage for one or more host processors in a system.
A host processor may perform a variety of data processing tasks and operations using the data storage system. For example, a host processor may perform basic system I/O operations in connection with data requests, such as data read and write operations.
Host processor systems may store and retrieve data using a storage device containing a plurality of host interface units, disk drives, and disk interface units. Such storage devices are provided, for example, by EMC Corporation of Hopkinton, Mass. and disclosed in U.S. Pat. No. 5,206,939 to Yanai et al., U.S. Pat. No. 5,778,394 to Galtzur et al., U.S. Pat. No. 5,845,147 to Vishlitzky et al., and U.S. Pat. No. 5,857,208 to Ofek. The host systems access the storage device through a plurality of channels provided therewith. Host systems provide data and access control information through the channels to the storage device and storage device provides data to the host systems also through the channels. The host systems do not address the disk drives of the storage device directly, but rather, access what appears to the host systems as a plurality of logical disk units. The logical disk units may or may not correspond to the actual disk drives. Allowing multiple host systems to access the single storage device unit allows the host systems to share data stored therein.
In connection with testing in a data storage system environment, it may be desirable to be able to test upper or maximum limits. For example, a maximum number of logical connections may be allowable between one or more hosts and a data storage system and it may be desirable to perform testing using conditions with the maximum number of connections. In data storage system environments in accordance with one version of a protocol or standard, such as the Fibre Channel (FC) protocol, only a single logical or virtual connection may be allowed for each physical connection such as between any pair of FC ports (e.g. such as a port of a host and a port of a data storage system). In such an environment, a large number of physical hosts and associated FC adapters (FAs) may be required to perform appropriate testing. The number of FAs and hosts required for testing the maximum number of logical connections allowable, as well as the time to configure such FAs and/or hosts, may not be practical or feasible to provide in a testing environment in accordance with FAs supporting the foregoing version of the protocol.
Subsequent or later versions of standards and protocols, such as the FC protocol, may provide support for multiple logical connections over a same physical connection. For example, N-Port ID Virtualization (NPIV) is part of a more recent version of the industry standard FC protocol which provides for multiple logical connections over a same physical connection between two physical FC ports. Hardware, such as ASICs (application-specific integrated circuits) utilized by vendors in such FAs, may provide support in accordance with the revised FC protocol and therefore support multiple logical connections over a same physical connection. FAs of the hosts may include the appropriate ASICs and other hardware to provide the foregoing virtualization in accordance with NPIV. However, data storage systems and/or hosts available for use in connection with the testing environment may not include the more up-to-date FAs which provide the foregoing virtualization in accordance with supporting NPIV. FAs available for use in the testing environments may rather not support NPIV and may be in accordance with the earlier FC protocol providing only a single logical connection over a physical connection.
As such, it may be desirable to utilize techniques in connection with testing environments as well as other purposes for emulating multiple logical connections over a single physical connection without requiring use of hardware that provides such support such as, for example, without requiring use of FAs or other hardware which provide support for NPIV in accordance with the FC protocol.